# General Chemistry/Useful Equations

 General Chemistry Book Cover · Introduction ·  v • d • e

### General

 Density: ${\frac {mass}{volume}}$ Moles: ${\frac {given~mass~(g)}{gram~formula~mass}}$ Percent Error: ${\frac {measured-accepted}{accepted}}\times 100\%$ Percent Composition (by mass): ${\frac {mass~of~part}{mass~of~whole}}\times 100\%$ Molarity: ${\frac {moles~of~solute}{volume~of~solution}}$ Molality: ${\frac {moles~of~solute}{mass~of~solvent~in~kg}}$ Rate of Reaction: ${\frac {Difference~in~quantity}{Difference~in~time}}$ de Broglie's law: $\lambda$ = ${\frac {h}{mv}}$ ### Atomic Structure

Symbol Meaning Symbol Meaning
$E$  energy $c$  speed of light
$v$  frequency $\lambda$  wavelength
$Q$  charge $r$  distance
$k_{e}$  Coulomb's constant $h$  Plank's constant H/nkne
 Energy of Wave: $E=hv$ Wave Relation: $c=\lambda v$ Coulomb's Law: $F_{e}=k_{e}{\frac {Q_{1}Q_{2}}{r^{2}}}$ ### Solutions, Liquids, Gases

Symbol Meaning
$P$  pressure
$V$  volume
$n$  number of moles
$T$  temperature (in Kelvin)
$K_{f}$  molal freezing point constant
$K_{b}$  molal boiling point constant
$\chi$  mole fraction
$m$  molality
$M$  molarity
$c$  specific heat capacity
$M_{w}$  mass of water (Kg)
$E_{h}$  heat energy released

 Rauolt's Law: $P_{solution}=P_{1}\chi _{1}+P_{2}\chi _{2}+\dots$ Boiling Point Elevation: $\Delta T_{solution}=K_{b}\cdot m_{solute}$ Freezing Point Depression: $\Delta T_{solution}=K_{f}\cdot m_{solute}$ Ideal Gas Law: $PV=nRT$ Combined Gas Law: ${\frac {P_{1}V_{1}}{n_{1}T_{1}}}={\frac {P_{2}V_{2}}{n_{2}T_{2}}}$ Titration: $M_{A}V_{A}=M_{B}V_{B}$ Dilution: $M_{1}V_{1}=M_{2}V_{2}$ Heat released by burning: $E_{h}=cM_{w}\Delta T$ ### Equilibrium

Symbol Meaning
$K_{eq}$  equilibrium constant (general)
$K_{p}$  pressure equilibrium constant
$K_{c}$  concentration equilibrium constant
$R$  gas law constant
$T$  temperature (in Kelvin)
$\Delta n$  moles of product – moles of reactant
 pH: $\mathrm {pH} =-\log {[\mathrm {H^{+}} ]}$ pOH: $\mathrm {pOH} =-\log {[\mathrm {OH^{-}} ]}$ (for water): $\mathrm {pH} +\mathrm {pOH} =14$ Pressure/Concentration: $K_{p}=K_{c}(RT)^{\Delta n}$ Equilibrium, for a reaction $a\mathrm {A} +b\mathrm {B} \rightarrow c\mathrm {C} +d\mathrm {D}$ : $K_{eq}={\frac {[\mathrm {C} ]^{c}[\mathrm {D} ]^{d}}{[\mathrm {A} ]^{a}[\mathrm {B} ]^{b}}}$ ### Thermochemistry

Symbol Meaning
$q$  heat energy
$m$  mass
$c$  specific heat
$T$  temperature (in Kelvin)
$S$  entropy
$H$  enthalpy
$G$  Gibbs free energy
 Heat Transfer: $q=mc\Delta T$ Enthalpy: $\Delta H=H_{products}-H_{reactants}$ Entropy: $\Delta S=S_{products}-S_{reactants}$ Free Energy: $\Delta G=\Delta H-T\Delta S$ 